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88娱乐城
Historically, this won鈥檛 be the first time a JWR mine has tackled such a feat. In the early 1980s, it had two active faces while the No. 3 portal, idled in 1999, had three. The No. 4 mine also ran three faces later that same decade.
鈥淭hose weren鈥檛 even comparable鈥� to what longwalls do now, said Thrasher. 鈥淲e do more with one now than we ever did with three, in terms of production.鈥�
While some additional changes and upgrades will have to be made, such as the doubling of its hoist capacity by installing a second production shaft, Kozel said No. 7 is ready to 鈥渉andle another high-capacity longwall鈥�
With the second face expected to go online in early 2009, easily doubling the capacity of the operation, the staff is in preparations for additional expansion through the development of a single panel in the southwest section of the complex. The intent, according to management, is to bridge tons by fall 2007 and then ramp up when the expansion longwall begins its work.
For the time being, its existing longwall and development workings are really a force to be reckoned with. Unlike No. 4, the mine only extracts from one seam (however, the mains are twin seam like No. 4).
No. 7 also has a good floor and main roof, as is evident upon entering the mine at about 1650ft. Trips to the longwall face take about 25 minutes, and personnel transport at both mines is achieved with diesel track mantrips.
The current F panel is also 850ft wide, but lengths vary between 9500ft and 13000ft. Again, the average-sized worker is comfortable with a 68in cutting height; the seam height averages 53in.
Online since 1984, the longwall face now cuts coal with a Joy 7LS1A shearer with a 38.5in x 64in diameter drum and 1324hp installed power. There are 147 DBT two-leg shields, each with a working range of 60-90in and 6200psi yield, which surround the face crew. A DBT PMCR system controls roof support activity.
JWR鈥檚 face conveyor, at 1000mm width, features 42mm x 146mm dual inboard Thiele galvanized chain running 305fpm powered by three Mohler 600hp motors. The crusher, also manufactured by JWR, has a 9in clearance to deck and 4in clearance to flite.
The 54in conveyor holds Goodyear and Scandura-produced conveying fabric, and four-ply 1350piw and 1000piw belts can carry 4750tph comfortably. Thrasher and outby manager Ty Olson said the most significant obstacle in this area is that it can convey more than the hoist鈥檚 current capacity.
Conveyor capacity works well for its rate of output, with a 3000tph AFC and BSL running 4000tph. At the end of the day with availability typically staying about 90%, the longwall has retreated 65ft with about 9500 clean tons leaving the face.
Panel changes are outlined well in advance, and the move itself usually takes 10 days after about three days of meshing. The next panel change at No. 7 will take place in August 2007.
Like its sister mine, the yield-stable-yield pattern is also instituted here. Four headings are driven for development with the average roadways measuring 20ft wide, 40ft center to center wide and 187.5ft long for yield with stable pillars 180ft x 375ft center to center.
Road support is achieved with the use of .804 x 72in Jennmar resin grouted bolts placed five every 5ft with a Fletcher bolter, plus the use of both propsetter timbers and cable bolts in the gateroads. Unlike No. 4, the No. 7 operation does not practice rib bolting unless the twin seam conditions in an area call for its use.
Standard development equipment begins with Joy 12CM12 and 12CM27 continuous miners, one of which was just replaced in early January. Jeffrey diesel ramcars, 488 S&S scoops and Stamler 200hp feeders make up the balance of the package at active sections, which, on average, run 250ft per day.
Maintenance is managed a number of different ways at No. 7, with the most significant being daily and weekly planned times in the schedule. A PM system and work order system are also used. To ensure the smooth relationship between operations and maintenance, daily meetings are held along with the input of planning staff.
The support the mine receives from its in-house shop and its OEMs is good, according to Thrasher. 鈥淸There are] routine service exchange and rebuild programs to keep equipment in good condition,鈥� he said.
One area of challenge that the mine has always had is gas. Both No. 7 and No. 4 work in tandem with another JWR affiliate, Black Warrior Methane, for degasification efforts.
Kozel said that process is accomplished in four ways, the first being to extract and sell using vertical wells in advance of mining. The second method involves the horizontal drilling of longwall panels, the results of which are piped outside.
Longwall gas, or gob gas, is the mine鈥檚 third way to tackle degassing. Lastly, the low quality gas production is sent to a cryogenics facility where it is stripped of the air and put back into a pipeline with quality gas.
No. 7鈥檚 625-person workforce works six days a week in three shifts of eight hours, broken down into 528 UMWA workers and 97 salaried employees. Of those, 458 frontline individuals and 67 salaried workers call underground their office. Six of those miners can be found every shift at the longwall face, while the CM section will staff 11.
The mine has a formal safety program that frequently utilizes the nearby JWR Training Center. Kozel said injury incidents at the mine have shown an improvement, having steadily dropped since 1998.
鈥淲e鈥檙e happy with the trend line,鈥� he said, and Thrasher concurred with the opinion that the workforce鈥檚 effort, and pride in their work, is key to those results.
Family resemblance
While the mines No. 4 and 7 do differ, some of their mining methods cross over. In addition to JWR鈥檚 own equipment provided to the mines, both have similar customers in South America, Europe and North Africa.
At both operations, coal is...click here to read on.
